The Radar Data Communication Interface was a Bureau implementation of the Alfatron A3000 Communications Interface. The Z80 based microprocessor unit was reprogrammed to provide a radar picture data storage and re-transmission function.
The hardware of the unit comprised a switch mode power supply, an A3000 modular interface card (the main CPU card) and a pair of A3010 serial interface cards. It was functionally two I/O ports communicating with a CPU with rom and scratch ram.
Modular Interface A3000
This Z80 microprocessor based card had 8k of eprom and 2k of ram, as well as 256k of bank switched ram. It was connected to a number of I/O mapped LEDs and switches. It had two Z80 I/O Bus extension connectors with some decoded I/O mapping for external peripheral cards. Two different CPU clock speeds of 4.3 Mhz and 3.07 MHz were used.
A watchdog reset timer modification was fitted by the Bureau to provided a CPU Reset if no IORQ signal occurred for more than one second, this meant if the unit should lockup it would automatically reset.
Serial Interface A3010
The Serial Interface provided one serial RS232C channel of I/O interface for the microprocessor card. It consisted of a 8251 Programmable Communication Interface with a 8253 Programmable Interval Timer which provided the programmable baud rate generation.